1. Field of the Invention
The present invention relates to a linear actuator.
2. The Prior Art
Linear actuators are widely used in structures where the linear movement can be used for adjusting a movable part of a structure. Thus, linear actuators are used in furniture, hospital and care beds, patient lifters, vehicles, ships and airplanes, machines and processing plants, buildings, etc. The actuator is typically secured to the structure by means of a rear mounting arranged at the back of the actuator and a front mounting on the activation element. The activation element is typically a tubular piston rod, but may also be a particular design of the spindle nut.
EP 0 531 247 B1 Linak A/S discloses an actuator where the rear mounting and the housing of the actuator is moulded as one unit. U.S. Pat. No. 4,858,481 Brunswick Valve & Control, Inc. discloses an actuator where the rear mounting as a separate unit is screwed onto the rear of the housing of the actuator. U.S. Pat. No. 5,809,833, Dana Corp. discloses an actuator where the rear mounting likewise is a separate unit, but is screwed onto an element inside the actuator. The rear mounting is here open in the front, where a bearing at the end of the spindle is positioned in and retained by means of a screwed on plate piece having a through hole for the spindle. WO 02/29284 A1, Linak A/S discloses an actuator, where the rear mounting consists of two halves which are joined in the axial center plane of the rear mounting. The rear mounting is furnished with a seat for a bearing, which is secured to the end of the spindle. All of the above are as such quite good constructions, but somewhat troublesome in terms of manufacturing and assembly as well as expensive.
To be exact, the invention relates to the type of linear actuators where the bearing is positioned in the rear mounting, which provides the advantage that the axial forces from the load on the activation element of the actuator are led directly through the spindle to the bearing of the spindle.
The purpose of the invention is to provide a rear mounting, which is easier to mount and further enables an easier handling during the assembly of the actuator.